编辑代码

public class Main {
    public static void main(String[] args) {
        Stu a = new Stu("张三", 12);
        Stu b = new Stu("李四", 13);
        exchange(a, b);
        System.out.println("--------------------");
        System.out.println("main a：" + a.name + "，" + a.age);
        System.out.println("main b：" + b.name + "，" + b.age);
    }

    public static void exchange(Stu a, Stu b) {
        Stu t = a;
        a = b;
        b = t;
        System.out.println("exchange a：" + a.name + "，" + a.age);
        System.out.println("exchange b：" + b.name + "，" + b.age);
    }
}